The Yerkes Obervatory Photographic Plates

Yerkes Observatory houses a collection of over 170,000 astronomical photographic plates. Almost all were taken in the twentieth century. Roughly 45% are direct plates, 45% slit spectra and 10% solar images, spectra or spectroheliograms. The majority of the plates were taken using the observatory's 40-inch refractor (Hale 1897), the former 24-inch reflector (Ritchey 1901) and the wide-field photographic telescope (Barnard 1905). There are smaller collections taken with other Yerkes telescopes as well as with instruments at the McDonald, Dearborn, Perkins and the University of Illinois Observatories. Of particular interest are the deep photographs taken by E. E. Barnard 1900-1923.

The Yerkes plate collection also has several thousand copies of photographs of comets, galaxies, nebulae, eclipses, telescopes, the Observatory and the like that were specially prepared for distribution.

Yerkes Observatory welcomes astronomers, writers and researchers to use the plate collection. Those interested in particular materials or in visiting are invited to contact the Observatory: